The present invention relates to stereo image forming or generating apparatuses for viewing, on the basis of computer graphics or like techniques and with adequate image display means, a plurality of stereo-modeled objects in a virtual space where three-dimensional coordinates are set, and more particularly to an apparatus capable of viewing of a particular one of the plurality of objects by providing an adequate parallax and without feel of departure from natural sense of viewing or feel of fatigue.
Stereo image forming apparatuses, for viewing, on the basis of computer graphic (CG) or like techniques, a plurality of stereo-modeled objects, either statically or dynamically, in a virtual space where three-dimensional coordinates are set, are recently being developed, and various pertaining apparatuses have been proposed or manufactured.
However, such stereo image forming apparatuses, unlike apparatuses for merely obtaining stereo display images free from parallax between images for the left and right eyes, should form two different kinds of images with a binocular parallax therebetween. The formation of such images usually requires a long time until obtaining desired image data, or requires a high performance computer.
Japanese Laid-Open Patent Publication No. 07-230557 proposes a method for generating CG stereo-viewing animation, in which a stereo-viewing effect is provided by permitting the viewer's left and right eyes to view respectively formed images. In this method, CG images constituting a left eye and a right eye images are subjected to field-by-field rendering (which is an operation for making three-dimensional modeling inputted to a computer to be visible on a display, refer to "Three-Dimensional CG", edited by the Association of Television Engineers, issued by Ohm Co., Ltd.), thus reducing time necessary for the rendering.
In the meantime, the stereo image forming apparatus has a problem that, a feel of departure from natural sense of viewing and also a feel of fatigue are caused to the viewer by a departure from a relation, which is given between the focus on the eyes (or accommodation), i.e., the distance of an image formed on a display for viewing images for the left and right eyes, from the viewer's eyes and the vergence corresponding to the parallax between the two images (i.e., natural effort of concentrating the visual lines of the two eyes on an object to be viewed, see Shuya Koyanagi, "Dictionary of Optical Technology Words", issued by Opto-Electronics Co., Ltd.). The viewer's fatigue is also caused by frequent changes in the parallax concerning images or image portions under attention.
Japanese Laid-Open Patent Publication No. 07-167633 shows a stereo image pick-up/display apparatus, in which an image of an object, picked up in two different directions using two cameras, is recorded and reproduced for display with a fixed parallax concerning the image or image portion of the object under attention.
The above method of CG stereo-viewing animation generation disclosed in the Japanese Laid-Open Patent Publication No. 07-230557, suggests no consideration on reducing the feel of departure or feel of fatigue in the viewing of stereo-modeled objects in a virtual space.
The method of the field-by-field rendering of CG images constituting a left eye and a right eye images, is only disclosed, and no specific means to this end is disclosed.
The apparatus disclosed in the Japanese Laid-Open Patent Publication No. 07-167633, is constructed to determine, from the binocular parallax of image, an optimum visual point which permits the viewer to perceive the depth world of an object in the broadest range, and control the reproduction such that the position of the object is at a predetermined depth direction distance from the screen position of an image display. To achieve this control, a parallax map is obtained by the left and right eye images by computation using a correlation matching method. Then, a mean parallax value of image is obtained, or a factor-multiplied (weighted) mean parallax value is obtained by factor-multiplying (weighting) the screen center image. Using such mean parallax, parallax control means controls horizontal position read timing of data corresponding to the left and right eye images.
In this system, however, parallax maps of the entire screens are obtained by frame-by-frame computation. Therefore, the computation is complicated, and requires relatively ling time until obtaining the result, unless the system can be constructed by using a computer having particularly high performance.